PVC的热解/红外(Py/FTIR)研究

采用热解／红外联用仪（Py/FTIR)考察了PVC的热解过程，结果表明，PVC在200℃时开始放出HCl,300℃左右达到最大，在红外谱图上HCl气体的振－转吸收区是3100cm^-1～2600cm^-1，有P支和R支出现；随后－CH2－基在2860cm^-1和2930cm^-1处的吸收明显增强，可认为是生成的多烯碎片进一步裂解生成脂肪族化合物的结果；同时有芳烃在1620cm^-1、3010cm^-1和900cm^-1～600cm^-1处的吸收出现。这是由于除了部分多烯碎片规则断裂形成酯肪烃类物质的挥发分外，还有一部分通过分子重排、环化形成芳烃结构，其中的一部分以芳烃类物质进入挥发分，另一部分聚合形成稠环芳香族物质，最后变成焦粒。通过上述研究，提出了PVC的热解机理，即PVC首先脱出HCl气体，进一步热解产生多烯结构，并通过分子重排、环化形成芳烃结构。     

稀土偶联剂对Mg(OH)2的改性作用及其在PP/Mg(OH)2体系中的应用

研究了稀土偶联剂(ReC)对Mg(OH)2的表面改性作用及PP/Mg(OH)2体系的燃烧性能、流动性能、力学性能及老化性能.稀土偶联剂可显著改善Mg(OH)2在非极性介质中的分散性;PP/Mg(OH)2体系当Mg(OH)2填充量超过50%时,氧指数(OI)≥28.5,但这时冲击强度不足纯PP的30%,熔体流动速率(MFR)低于0.6g/10min;而填科用2.59%(质量)ReC处理后,填充量为50%的体系冲击强度接近纯PP,MFR达2.8g/10min;Mg(OH)2对体系光氧老化过程有加速作用,而对热氧老化过程有阻滞作用;稀土偶联剂对体系光氧老化过程有轻微的促进作用,而对热氧老化过程无明显影响.     

Ni2P/Cu(OH)2催化剂的制备及其全解水性能研究

通过化学处理法在泡沫铜基底表面生成Cu(OH)₂纳米线,大大增加了基底材料的表面积和导电性.采用水热法在Cu(OH)₂纳米线表面制备片状Ni-CH/Cu(OH)₂前驱体,对Ni-CH/Cu(OH)₂前驱体进行低温磷化得到多级结构Ni₂P/Cu(OH)₂催化剂.通过扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)和X射线衍射仪(XRD)对催化剂的物质结构和表面形貌进行了表征.采用线性伏安法、恒电位等技术对催化剂的电化学性能进行测试.在1.0 mol·L^-1 KOH碱性溶液中,当电流密度为10 mA·cm^-2时,Ni₂P/Cu(OH)₂的析氢反应(HER)和析氧反应(OER)过电位分别为133和333 mV,且均具有较好的稳定性.将这种多级结构Ni₂P/Cu(OH)₂催化剂分别用作阳极和阴极进行全解水电解,电流密度达到10 ...     

配位化合物[Cd(hca)2(H2O)3](H2O)2，[Cu(hca)2(phen)]的合成与表征

配合物1由醋酸镉和Nahca(对羟基肉桂酸钠)在水溶液中反应得到,配合物2由醋酸铜,Hhca和phen在水和乙醇混合溶液中反应得到。配合物1属正交晶系,Pbcn空间群。配合物2属单斜晶系,C2/c空间群。配合物1和2中配体中的羧酸根与金属离子都是螯合配位的,末端羟基没有参与配位。配合物1和2的结构中都包含了丰富的氢键。通过氢键作用,配合物1形成了三维网状超分子结构,配合物2形成了二维层状超分子结构。     

配合物[Cr3(μ3-O)(Tc)6(H2O)3]·(NO3)·4H2O的水热合成及晶体结构

通过有限个过渡金属离子如Fe,Ni,Cr,Mn与O、OH、-O或-O2CR等桥联原子或基团键合形成的具有不同尺寸的环形轮状金属离子簇合物或分子簇合物是近年来的研究热点之一[1,2].它们不仅具有独特的结构,而且在催化、非线性光学、分子自组装等方面具有潜在的应用价值[3～5].特别是具有三角型结构的过渡金属-氧轮簇化合物由于可以作为单分子磁体的磁性交换和电子耦合的研究体系,引起了研究人员的极大地兴趣[6,7].研究表明,具有[M(μ3-O)(O2CR)6L3]0/+,(M=Fe3+或Mn3+,L为水或吡啶,R为烷基或芳香基团)结构的化合物具有反铁磁作用[8,9].     

球型Ni(OH)2表面包覆Y(OH)3及其高温充放电性能

应用共沉淀的方法在球型Ni(OH)₂的表面包覆了一层Y(OH)₃,并研究了包覆不同含钇量后的球型Ni(OH)₂的高温充放电性能。研究结果表明:包覆Y(OH)₃的球型Ni(OH)₂具有良好的高温充放电性能。其中1C充放电条件下,包覆量为0.3%的Ni(OH)₂较好,0.2C充放电条件下,包覆量为1%的Ni(OH)₂较好。     

［Ln(EO2)3］(ClO4)3·3H2O的晶体结构研究

合成了希土高氯酸盐开环冠醚二缩乙二醇(EO2)晶体，(Ln=Nd, Ho)，测定了结构，文内以Nd-L的数据为主要研究对象(方括号内是Ho-L的数据)。晶体属单斜晶系，P2₁/n空间群，化学式［Ln(EO2)₃］(ClO₄)₃·3H₂O，晶胞参数为：a=14.124(1)［14.087］, b=13.990(1)［14.039］, c=15.265(1)［15.014］?; β=95.78(1)［95.64］°; V=3001.1(6)［2955］?³; Mr=815.01［835.70］; Z=4; Dc=1.804［1.865］g/cm³；石墨单色器，μ(MoKα)=2.09［3.07］ mm^-1，最终偏离因子R=0.055［0.074］, R_W=0.071［0.109］。研究结果表明晶体具有相同的结构，配位多面体为九配位三帽三棱柱。发现EO2醚链有绕C-C键呈STT分布的规律。弱配体高氯酸根不参加配位。     

(H2O)2和(HCl)2非线性光学性质的从头计算研究

用MP2方法及aug-cc-pVDZ,aug-cc-pVDZ+BF,aug-cc-pVTZ和aug-cc-pVTZ+BF基组对(H2O)2和(HCl)2超分子的静态偶极矩μ0,极化率α0及第一超极化率β0进行计算.采用Counterpoise方法消除基组的重叠误差(BSSE),得到上述物理性质的分子间相互作用的贡献,在此基础上研究了其中新的长程π型氢键的效应.     

发光PtⅡ-CuⅠ异核配合物[Pt4Cu2(edt)4(PPh3)6](ClO4)2(4H2O)的合成及其表征

Self-assembly between Pt(phen)(edt) (phen=phenanthroline, edt=1,2-ethanedithiolate) and [Cu(PPh₃)₂(MeCN)₂](ClO₄) (PPh₃=triphenylphosphine) gave rise to formation of heterohexanuclear complex [Pt₄Cu₂(edt)₄(PPh₃)₆](ClO₄)₂(4H₂O) (1). The complex was characterized by elemental analyses, ES-MS, UV-Vis, IR, ³¹P NMR spectroscopy and X-ray crystallography. The molecule consists of two [Pt₂Cu(edt)₂(PPh₃)₃] units which has a centrosymmmetric inversion to give a cyclic heterohexanuclear skeleton. The Pt^Ⅱ and Cu^Ⅰ center adopt square-planar and trigonal coordination modes, respectively. The compound shows intense emission at 632 nm in the solid state and at 678 nm in frozen dichloromethane glass at 77 K.     

温度对三元正极材料前驱体Ni0.65Co0.1Mn0.25(OH)2理化特性的影响

以类球形的Ni_(0.65)Co_(0.1)Mn_(0.25)(OH)_2前驱体为研究对象,系统地研究了处理温度对该前驱体的比表面积、形貌、粒径、金属含量等理化指标的影响规律。通过X射线衍射、热重、X射线光电子能谱等检测手段揭示了高温处理过程中前驱体物相演变行为、热稳定性以及过渡金属元素的价态变化规律。     

苯乙烯/聚氯乙烯接枝膜的热稳定性研究

用自由基悬浮聚合法合成了苯乙烯 /聚氯乙烯接枝膜 ,并对产物热处理 ,然后进行紫外 -可见光谱 ,红外光谱 ,热失重分析。结果表明接枝苯乙烯后的聚氯乙烯膜热稳定性得到了提高。同时 ,讨论了热稳定性机理。     

Improvement of Structural and Thermal Stabilities of PVC and Wood/PVC Composite by Zn and Pb Stearates,and Zeolite

Three different chemical stabilizers were introduced into neat PVC and a wood/PVC composite (containing 50 phr wood flour) to improve their thermal and structural stabilities. The changes in CIE yellowness index, polyene index, %wt loss, and decomposition temperature (T_d) were monitored. The effects of type and content of thermal stabilizers, thermal ageing time, and the presence of wood flour were our main interests. The experimental results suggested that the additions of Zn and Pb stearates into PVC and wood/PVC composite could improve the thermal stability of the PVC. At the test temperature of 177°C, the additions of Zn and Pb stearates could improve the thermal stabilities of PVC by retarding the upzipped reaction and by reducing the conjugated double bonds in PVC, Pb stearate being the most suitable for thermally stabilizing the PVC. Around the T_d range (～264°C), the addition of Zn stearate reduced the T_d value of PVC whereas that of Pb stearate had no effect on the change in T_d value. Zeolite loading could shift the T_d value of the PVC from 264 to 280°C. The addition of wood particles increased the polyene content and decreased the decomposition temperature of the PVC. The effect of wood flour on the thermal and structural changes of PVC overruled that of thermal stabilizer loading.     

PVC硬脂酸轻稀土热稳定剂的复配与应用研究

为了进一步研发性价比高且"无铅化"的稀土复合热稳定剂,研究了系列硬脂酸轻稀土盐(镧/铈/镨/钕/钐/铕/混合)与其他常用PVC热稳定(助)剂的复配效果。通过刚果红试纸法、红外光谱分析(FT-IR)、转矩流变仪等探究了复合热稳定剂对PVC性能的影响。结果表明:复合热稳定剂配方为硬脂酸轻稀土盐0.7~1.0份、硬脂酸锌0.8~0.9份、β-二酮0.3~0.6份和季戊四醇0.8~0.9份。将3份复合热稳定剂添加到100份PVC树脂中,静态及动态热稳定时间延长至100和35 min左右;动态热稳定性能和力学性能优于市售钙锌热稳定剂,与市售铅盐较接近。红外光谱分析表明复合热稳定剂可在加热初期减缓PVC氧化降解,较好地抑制初期着色,对PVC性能影响顺序为:镧组钕组混合组铈组镨组钐组铕组。     

Overview of the recent literature on flame retardancy and smoke suppression in PVC

This paper presents an overview of the recent literature on flame retardancy of poly(vinyl chloride) (PVC). A short overview of mechanisms of thermal decomposition of PVC, especially those which lead to char formation, is also presented because this gives insight into the mechanisms of flame retardant action. New developments in the area are mostly focused on combinations of various flame retardants and smoke suppressants in the search for synergistic effects. Because different additives show different mechanisms of action, synergistic combinations are very probable. New developments in phosphate ester plasticizers are reported in the literature. Copyright © 2005 John Wiley & Sons, Ltd.     

Allylated PVC

Active chlorines in poly(vinyl chloride) (PVC) were quantitatively replaced by pendant allyl groups ( CH₂CHCH₂) with allyltrimethylsilane in the presence of Friedel–Crafts acids (e.g., Et₂AlCl and TiCl₄). The thermal stability of the allylated PVCs was significantly superior to that of the starting material. Our allylation method is essentially quantitative; indeed, it was used for the determination of the active chlorine content in the PVCs. Furthermore, the pendant allyl groups were quantitatively oxidized by m‐chloroperbenzoic acid to epoxides; thus, PVCs carrying propylene oxide substituents [ CH₂CH CH₂(O)] were prepared. The structures of the products were characterized by high‐resolution NMR spectroscopy, and their thermal characteristics were characterized by TGA and color formation. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 307–312, 2001     

Effects of Epoxidation Content of ENR on Morphology and Mechanical Properties of Natural Rubber Blended PVC

This research work has concerned a study on toughness of PVC/natural rubber (NR) blends compatibilized with epoxidized natural rubber (ENR). The aim of this work was to investigate the effect of degree of epoxidation on morphology and mechanical properties of the blends. Epoxidized natural rubber with a variety of epoxidation contents were prepared by reacting the NR latex with formic acid and hydrogen peroxide at various chemical contents. Chemical structure and epoxidation content of epoxidized natural rubber were evaluated by FTIR and ¹H-NMR techniques. After that, three grades of ENR with epoxidation contents of 15, 25 and 42 % (by mole) were further used for blending with PVC and NR in an internal mixer at 60 rpm and at 170 °C. From tensile and impact tests, it was found that tensile elongation and impact strength of the materials remarkably increased with degree of epoxidation. On the other hand, tensile strength and modulus of the materials rarely changed with the epoxidation content. An increase in toughness of the blends with epoxidation content was related to a better molecular interaction between PVC and ENR as suggested by torque-time curves of the materials.     

FTIR Study of the Thermal Degradation of Poly(vinyl Alcohol)

The degradation of poly(vinyl alcohol) was investigated using TG analysis and Fourier transform infrared spectroscopy to determine the effect of atmosphere on the process of degradation. In the spectra, four vibrational modes were identified that characterised the major steps of the degradation process. These were the O-H, C-H, C=O and C=C stretching modes. The mechanism observed for degradation in an inert atmosphere was in accordance with the accepted mechanism of elimination followed by pyrolisation. Evidence of conjugated polyenes, however, was not observed. For the air atmosphere, oxidation in both steps of the degradation process was observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Flammability and Thermal Oxidative Degradation Kinetics of Magnesium Hydroxide and Expandable Graphite Flame Retarded Polypropylene Composites

The flammability and the thermal oxidative degradation kinetics of expandable graphite (EG) with magnesium hydroxide (MH) in flame‐retardant polypropylene (PP) composites were studied by limiting oxygen index (LOI), UL‐94 test, and thermogravimetric analysis (TGA). The results show that EG is a good synergist for improving the flame retardancy of PP/MH composite and the effect is enhanced with decreasing EG particle size. The Kissinger method and Flynn‐Wall‐Ozawa method were used to determine the apparent activation energy (E) for degradation of PP and flame retarded PP composites. The data obtained from the TGA curve indicate that EG markedly increases the thermal degradation temperature of PP/MH composites and improves the thermal stability of the composites. The kinetic results show that the values of E for degradation of flame retarded PP composites is much higher than that of neat PP, especially PP/MH composites with suitable amount of EG, which indicates that the flame retardants used in this work have a great effect on the mechanisms of pyrolysis and combustion of PP.     

氢氧化铝镁正电溶胶制备及性能研究

氢氧化铝镁正电溶胶制备及性能研究侯万国，张春光，孙德军，梁晓丽，王果庭（山东大学胶体与界面化学研究所，济南，２５０１００）关键词混合金属氢氧化物，溶胶，超细颗粒混合金属氢氧化物的合成、组成及结构等已得到广泛研究［１，２］．我们也曾用插入法合成了混合金...     

力化学降解对聚氯乙烯加工流变行为的影响

采用Brabender塑化仪和毛细管流变仪研究了经力化学降解制得的聚氯乙烯(PVC)的加工流变行为。结果表明,降解的PVC塑化时间比未降解的PVC明显缩短,塑化速度和熔化效率也明显加快,熔体粘度及玻璃比温度降低。